Hi Jos,
The MOSFET is a voltage driven device. Make sure that the device is fully enhanced by giving a gate voltage greater than 10volts, which will greatly increase the charge in the inversion layer( or conduction layer ) and reduce Rds(drain to source resistance). Since its a voltage controlled device people generally over look at the drive requirement.
Mind you that a weak drive or any input signal noise voltage greater than 20volts can puncture your gate oxide layer permanently destroying your device.
To keep the input impedance low try to connect 470E resistor from gate to ground. Make sure your drive can both source and sink 100ma +. Use a totem pole or npn-pnp combination as the drive. Use a free wheeling diode across the mosfet if it does not have a bultin reverse diode. you can also play with the Dc resistance value of the inductor such that under saturation the current does not exceed the device rating .
Regards
Raghunathan.
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